It can be particularly challenging to view images on small devices such as cell phones, mobile computers, and personal digital assistants (“PDAs”). These devices typically have a very small display area in which to display an image. To display an image, the devices may use software and information that is designed for devices with much larger display areas. For example, these devices may use a web browser to display standard size web pages. If an image in a high resolution is displayed in such a small display area, the image may need to be displayed in a much lower resolution to fit the entire image. With such a low resolution, however, the user may not be able to see the details of the image. Alternatively, if the image is displayed in full resolution in a small display area, only a small portion of the image can be displayed at once. To view other portions of the image, the user needs to navigate (e.g., scrolling and zooming) to view those portions. Because such devices are typically very small, it can be difficult for a user to perform such navigation.
Currently, most image browsers used by small devices offer only a simplified set of user interface features that are directly ported from a desktop image browser. Few designers of image browsers, however, take the characteristics of a small device into consideration when designing their user interfaces. Small devices are different from larger devices in input capabilities, processing power, and screen characteristics. For example, since small devices usually do not have a keyboard or mouse, it can be difficult to navigate around an image. Since small devices do not have the processing power of their large-device counterparts, it can be time-consuming to open high-resolution images, browse a large number of images, edit large images, and so on. The primary difference from a user's perspective is display area size. Because the display area is small, a user is forced to scroll and zoom in to areas of interest. Such scrolling and zooming are typically not necessary on a device with a large display area.
Attention models for images have been developed to help improve the experience of a user viewing an image on a small display area. Attention models seek to identify objects, referred to as “attention objects,” within an image that may be the focus of user attention and thus of interest to a user. For example, an attention model may seek to identify faces or text within an image as being areas that may be of interest. The attention models may calculate a score, referred to as an “attention value,” of likely user interest in each attention object. When the image is displayed, an image browser can use the attention model to direct the user's attention to attention objects with high attention values. By displaying portions of an image based on the attention values of the attention objects, an image browser can focus user attention to areas of the image that are likely to be of interest and thus reduce the navigation needed to locate areas of interest.
A difficulty with current attention models, however, is that they focus on identifying attention objects from the content of the image itself. It can be very difficult to develop an effective algorithm to identify areas that may be of interest for images covering diverse domains. For example, the areas of interest for an architect and a meteorologist in an image of a city skyline may be vastly different. As another example, a face in an image of a portrait may be of interest, but a face in an image of fans at a football game may not be of interest. As such, it would be desirable to have a technique to effectively identify areas of user interest within an image.